a Institute of Horticulture, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
b School of Agriculture and Food Science, Zhejiang A & F University, Lin'an, Hangzhou 311300, China.
Genome. 2018 Aug;61(8):595-604. doi: 10.1139/gen-2017-0215. Epub 2018 Jun 29.
Seedlessness is a highly desirable trait in citrus varieties. Sterility is the key determination for seedlessness formation. However, the molecular basis for female sterility in seedless mandarin remains unclear. Thus, a seedless Ponkan mandarin (Citrus reticulata Blanco 'Lipeng No.2'), considered the bud mutation of normal seedy Ponkan, was collected to identify candidate genes involved in seedless variation. Suppression subtractive hybridization (SSH) screened 1091 uniESTs related to seedy and seedless Ponkan (727 singlets and 364 contigs), which mainly governed catalytic activity, transferase activity, and oxygen binding. By using RNA-Seq technology, 106 differentially expressed genes (DEGs) were captured, of which 74 were up-regulated and 32 were down-regulated. Gene Ontology and pathway analysis showed that six DEGs were enriched in the biosynthesis of secondary metabolite, whereas five DEGs were enriched in the signaling of plant hormones. The combined results of SSH and RNA-Seq indicated the importance of amino acid metabolism in seedless Ponkan. Our findings revealed that the mechanism of seedless Ponkan generation may be related to gene regulation, signal cascade, and hormone levels. This study provided a solid foundation for functional gene identification in seedless Ponkan and a good reference for relevant research on molecular mechanisms of female sterility in Ponkan mandarin.
无核性是柑橘品种中非常理想的性状。雄性不育是无核形成的关键决定因素。然而，无子蜜柑的雌性不育的分子基础仍不清楚。因此，收集了一种无子碰柑（Citrus reticulata Blanco 'Lipeng No.2'），认为是正常有核碰柑的芽变，以鉴定参与无核变异的候选基因。抑制性消减杂交（SSH）筛选了 1091 个与有核和无子碰柑相关的 uniESTs（727 个单基因和 364 个基因簇），这些基因主要控制催化活性、转移酶活性和氧结合。利用 RNA-Seq 技术，捕获到 106 个差异表达基因（DEGs），其中 74 个上调，32 个下调。GO 和通路分析表明，6 个 DEGs 富集在次生代谢物的生物合成中，而 5 个 DEGs 富集在植物激素的信号转导中。SSH 和 RNA-Seq 的综合结果表明，氨基酸代谢在无子碰柑中很重要。我们的研究结果表明，无子碰柑的产生机制可能与基因调控、信号级联和激素水平有关。本研究为无子碰柑功能基因的鉴定提供了坚实的基础，也为碰柑雌性不育的分子机制相关研究提供了很好的参考。
